Troubleshooting

No doubt about it, there is nothing quite as painful as the sound of planer knives or a new carbide saw blade meeting metal in the middle of a board. With recycled lumber in fashion these days, hidden metal is a problem now more than ever. Old barn wood and wood from shipping pallets is in vogue, and there’s no telling what nails, screws, and other hardware the recyclers may have missed when they disassembled somebody else’s handiwork.
I first encountered such dangers many years ago, when customers asked me to cut down old picture frames. I’d pull any visible nails, but broken-off tips often lurked in the corners, waiting to take big bites out of my expensive chopper blades. What saved me from considerable future grief was the purchase of a battery powered electronic stud finder, the kind that lights up near metal. So far, it’s never let me down. Today, there is an even broader range of metal detectors that would do the job – the treasure detectors that beachcombers use, for example, or even the high-tech wands that security guards use at airports to foil felons. Whichever type you choose, if you use recycled lumber, a detector will probably pay for itself faster than any other shop accessory. One thing’s for sure: If there’s metal in your wood, better to find it before it finds you! An ironic note is that a lot of metal in sawed logs comes from hunters who have shot trees in frustration. Pieces if iron and steel in recycled wood can give the wood a chance to shoot back, so always observe safety precautions and wear appropriate safety gear.

“Filling and Staining Gouges”

Problem: I am refinishing a blanket chest that appears to be made of walnut. One piece has some gouges that I would like to fill before staining. Is there a filling material that will accept stain to match the rest of the piece?

Solution: Sad to say, most fillers do not accept stain in quite the same way that wood does. However, some are better than others. The best I’ve found is 3M’s Just Like Wood Filler. To prevent problems, get the filler as close as you can to the lightest value in the walnut. Let it dry on a sample scrap first, and then stain it to see how it takes stain. (some may end up too dark) If you are happy with the results, go for it. Remember that if you stay on the light side, you always have the option of putting in some grain lines or darkening the patch with a touch-up brush after the first coat of finish has dried.

“Filling Knotholes”

Problem: An otherwise perfect board has a knothole. How can I best fill it without detracting from the beauty of the board?

Solution: If you want to conceal the knothole, look for an area on a scrap piece of wood where the grain forms circles or has a pleasing irregular shape that will blend with the wood around the knothole. You might even find a tight knot in a similar piece of wood. If you just want to fill the hole without concealing it, choose a very dark piece of scrap that resembles the color of the missing knot. Saw and file a plug that fits well at the surface. The fit won’t be perfect in any case, but the surface fit is the most important. The trick is to glue in the plug with a filler made from sanding dust and epoxy glue. The epoxy will glue the plug in place, while the sanding dust will fill any imperfections. Of course, if you have the missing knot, you can just glue it in with the epoxy filler.

“Fixing Dents and Gouges”

Problem: I dropped a big chisel onto a tabletop, leaving a wide gash in the wood. It’s too big to fill with putty. What else can I do?

Solution: Gashes, gouges, and deep dents can be repaired by gluing in a wood patch from a piece of similar wood, ideally a cutoff from the same board. Use a small carving gouge to create a concave cavity that can be filled with a convex piece of wood. Carve gently in the direction of the grain so that you are forming crisp edges along the opening. Taper the opening to rounded points at its ends, like a canoe or elongated football. This shape avoids abrupt grain joints between the patch and the work piece. To shape the patch, file the edge of a piece of scrap so that its cross section is convex and it approximately matches the concave shape of the opening. Then cut the patch from the edge of the board and file or sand it to fit the overall shape of the opening. It does not need to fill the entire depth of the opening, but it should be at least 1/8 inch thick. In hardwoods, fit the patch so that it matches the opening cleanly. With softer woods, pressure from the clamp will mold the patch somewhat to the opening. Glue the patch into the epoxy. Then hand plane the patch so that it is even with the surface. Sanding alone usually leaves an obvious mound.

“Fixing Scratches”

Problem: As I was moving a coffee table from my shop to the house, I bumped into the door frame and scratched the top. Can I fix this without re-sanding and refinishing the entire top?

Solution: Surface scratches may look slightly white from abrasion, but that doesn’t mean that they have gone deep enough to remove the color from the wood. If that is the case with your scratch, you may be able to rub it out. Sand the area carefully with 600-grit wet/dry sandpaper using mineral spirits or soapy water as a lubricant. You want to abrade the surface just enough to remove the scratch but not enough to cut through the entire finish. If this removes the scratch, you then can bring back the original sheen by rubbing out the surface. Use steel wool and paste wax for a satin finish or automotive polishing compound for a gloss finish. If the scratch did not go down to the wood but is too deep to sand out, use a toothpick or a dine brush to carefully lay more finish into the scratch. Let it dry and repeat the process several times until the finish on the scratch is slightly proud of the finish on the rest of the surface. This process is called “doping in”. When the last coat of finish is dry, sand the proud area with 600-grit sandpaper and a lubricant, then rub out the surface as described above. If the scratch is on thin, penetrating oil finish, you can usually re-sand the spot, start with 220-grit sandpaper and moving up to 600-grit sandpaper, then reapply the oil finish to the area. If the finish is fairly new, reapplied oil finish should hide the spot well.

“Fixing Small Gashes”

Problem: I just discovered a small gash in my new hall table. The wood fibers are torn, so I can’t steam it out. How can I disguise the damage?

Solution: If the table has a film-type finish, the best bet is to use a burn-in stick to fill in the gash; then touch up the spot with paint to simulate the grain of wood. Burn-in sticks are made from solid, colored shellac or lacquer. To use one, just heat the end with a special burn-in knife (a heated screwdriver will do in a pinch). This melts the finish so that you can puddle it into your gash. To make your job simpler, mask off around the gash with 3M fine line tape, a very thin tape that will not damage the finish. It is available from auto supply stores. Choose a burn-in stick that corresponds to the LIGHTEST background color you can find in the wood. Melt the burn-in stick into the hole, overfilling slightly. If the blade of your knife has a flat end, let the knife cool a bit and then scrape across the burn-in lightly to level the burn-in to the tape. Otherwise, sand the burn-in flat to the tape. Now remove the tape and sand the last bit of raised burn-in using 600-grit wet/dry sand paper wrapped around a small bock. Be careful not to sand the surrounding finish too much or you will penetrate the finish. When the surface is level, you can touch up the spot. I like to use finely ground touch-up powders mixed into shellac or padding lacquer. Since you already established the background color by using a light burn-in stick, you need only add the darker grain lines to make the spot all but disappear. After the touch up has been completed, finish the surface with French polish or a light topcoat to blend it with the area you worked on. Buff or steel wool the final surface (depending whether it is a gloss or satin) and you are back in business. Incidentally, although you may do a good enough job on the spot so that no one else notices it, you will always see your own touch up. You might want to place something artistically on or near the spot after it has dried, just to distract your eyes, if no one else’s.

“Ironing Out Dents”

Problem: I dropped my sander onto my freshly sanded tabletop. Is there a way to remove the dent without having to start over?

Solution: Nothing lifts up little dents like a little steam. Steam softens and expands the wood fibers, allowing them to return to their original shape. For raising a dent, you have a choice of tools. Wood burning pens and clean soldering guns are commonly used and are good for supplying heat right where you want it. When using these tools, puddle a few drops of water on the dent. After allowing the water a couple of seconds to sink in, touch the tip of the pen or gun to the water and steam away the puddle. The trick with this technique is to not touch the wood with the heat element – you don’t want to scorch the wood. Another tool and one I prefer is a small travel iron. Although it tends to raise the grain more around the surrounding surface, an iron is easier to hold and you can adjust the temperature, which reduces the chance that you’ll burn the wood. I set the iron to “cotton” apply a damp cotton rag over the dent, and iron away. Don’t let the iron touch the wood itself; it’s not as likely to burn as the wood burning pens and soldering guns, but it can stain certain woods like oak. After steaming the wood, allow the piece to dry overnight. Then lightly sand the surface with 220 grit or finer grit sandpaper to knock off any whiskers raised by the extra steam.

“Repairing a Burn Hole”

Problem: A candle fell over on an oak dining table I just made and finished with lacquer. We caught it quickly, but not before it melted a dime-sized hole in the finish. It didn’t seem to char the wood, since the color has not changed. How can I repair the hole without refinishing the entire table?

Solution: Spray light coats of lacquer through a hole in a card until you have built up the finish so that it is level. Make the hole in the card about the same size as the crater in the finish, and hold the card just above the finish so that the card doesn’t stick to it. Use lacquer with the same sheen (gloss, satin, flat) as the one you used originally. Work slowly, allowing each coat of lacquer to cure hard. After you’ve filled the hole, let the lacquer harden for several days. Then sand it level, backing the sandpaper with a small flat cork or felt block. Rub the area with an abrasive, such as steel wool, pumice, rottenstone, or commercial rubbing compound, so that it matches the rest of the table. If you can’t match this sheen, you’ll have to rub the entire tabletop to an even sheen, which is still a lot less work than refinishing.